Author Topic: newbie with a problem (Read 6724 times)

duck · « **on:** November 10, 2005, 03:18:06 AM »

Hi all

i hope your wisdom will help me sort this out quickly.

i have a bandit 6 thats firing on three cylinders (second from left is not firing) it happened then went away then happened, went away..etc then after it hadn't been started for a week it stayed like it. we tested an ignition box off a gsx600f (no joy), the coils test ok and there is a good spark. is it likely to be the carb? and if so what can i do about it? the diaphram looks in one piece and the float appears to be working but i'm not really sure where to go from here

Any and i mean any info on what it could be would be greatfull as i am now stumped!!

zeebandit · « **Reply #1 on:** November 10, 2005, 10:09:14 AM »

For a quick check on the spark plug, switch #3 plug with a cylinder plug that's firing. I had a similar problem with my B12 and it was the plug.

duck · « **Reply #2 on:** November 10, 2005, 10:25:57 AM »

already tried that

PitterB4 · « **Reply #3 on:** November 10, 2005, 12:19:14 PM »

Is it only dropping that cylinder at idle (does it kick-in as the revs climb)? If so, you probably have a blocked pilot jet. You might be able to remedy that with some fuel additive. More likely you'll have to pull the carbs.

duck · « **Reply #4 on:** November 10, 2005, 01:53:48 PM »

no it's there all the way. it's as if it's an ignition problem but it's obviously not. could it be anything else other than the carb? it's wierd that it just stopped working after sitting there for a week

Daytona · « **Reply #5 on:** November 10, 2005, 02:20:34 PM »

I had the same thing happen on #4 cyl @ idle though! Do you get any sighn of fuel on the plug? What i did, that has cleared many briggs, bikes,etc is chock out that cyl @ the carb! It worked on my problem! The screen in the air box between the filter and carbs have to be removed, along with tank etc to get to filter area. I used a paint can top, rev up and choke! sounds kinda cave man but FM!!! works for me! add seafoam fuel addative, and a carb sync, and with a bit of luck it will run better than it did new! like mine now! GOOD LUCK

duck · « **Reply #6 on:** November 10, 2005, 03:06:39 PM »

...chock out that cyl @ the carb...? do you mean block off the carb intake then remove, block, remove and see if that works? i can't see any fuel on the plug

Daytona · « **Reply #7 on:** November 11, 2005, 11:37:56 AM »

Quote from: "duck"

...chock out that cyl @ the carb...? do you mean block off the carb intake then remove, block, remove and see if that works? i can't see any fuel on the plug

] Hey i meant choke! Yes block off the intake to the one not getting fuel. I used a spray paint plastic top, from inside the air box. Rev the eng up a bit 2 to 3k and choke off. Be ready to remove it or shut down eng! it will pull alot of fuel up from the bowl so you don't want too much. The fuel tank will need to be where you can get to the airfilter box and the screen will have to be removed. Don't even try to put it back! it must be a trade secret. Then after mine cleared up i used the seafoam i got from autozone for a few tank fulls and it ran as good as it ever did! Also this will tell if your valves are ok! If the paint can top isn't sucked tight! that means a valve problem or some thing in the comp area isn't rite, so it does more than get the crud out of your carb. good luck!

duck · « **Reply #8 on:** November 12, 2005, 05:24:28 PM »

you're not wrong about it pulling a lot of fuel through, my hand got covered and it nearly sucked the plastic lid in when we blipped the throttle

After we sealed the airbox back up it sounded better, smoother but still not right. keeping the throttle steady at about 10 mph in 1st it was jerking but accelerating it seemed to smooth out. After a quick 8 mile run to see if it would clear it was back to not firing at all and sounded as it did before.

forgot to mention the revs take longer to die down to idle.
what can i try now?

Daytona · « **Reply #9 on:** November 12, 2005, 06:00:24 PM »

Quote from: "duck"

you're not wrong about it pulling a lot of fuel through, my hand got covered and it nearly sucked the plastic lid in when we blipped the throttle
After we sealed the airbox back up it sounded better, smoother but still not right. keeping the throttle steady at about 10 mph in 1st it was jerking but accelerating it seemed to smooth out. After a quick 8 mile run to see if it would clear it was back to not firing at all and sounded as it did before.

forgot to mention the revs take longer to die down to idle.
what can i try now?

sounds like the primary system is being plugged, but that shouldn't have much to do with running above say 4k rpm! I have heard of the seafoam doing magic if you fill the carb's and let it sit over nite. If the suck job worked some what! that pretty much tells its in the carb! the lingering rpm's is a sign of a lean condition! sounds screwy but true! adjust your primary screws to about 2.25 to 2.5 turns out from in all the way in? also the 600 is very touchy with any airbox mods! holes, leaks, K&n filter! it gets all the air it can use with stock filter and box in stock shape! any leaks and it won't run rite! make sure the bottom tabs of cover is in slots. Have you drained the carb for water? carbs being out of sync at linkage can do this but it needs to be running better or at least idling to use the vac hoses.

duck · « **Reply #10 on:** November 13, 2005, 11:49:39 AM »

right, just throw a spanner in the works this is what happened today....

checked the pilot jet and it was out 3 turns. i screwed in to 2.25 and then to 1 7/8 (uk spec). they both seemed better than last night but after the engine was warm it appered to run a bit rougher???...thinking about it this is what happened last night, the engine was better when cold just running up and down in 1st then after a run it wasn't firing???...

just to double check we swapped plugs 1+2 over (2 not working) and ht leads 2+3 over and guess what...now number 3 cyl exhaust pipe was cold and 2 was hot (although not as hot as the outer two? )
i tested the coil the other day and it tested ok i didn't have my meter on me today to do it again.
do the coils send voltage down both caps at the same time? basically even though there are 2 leads poking out of one box does it work as one unit

maybe it is an ignition fault?????

duck · « **Reply #11 on:** November 13, 2005, 12:43:36 PM »

now i'm really confused... looking in the haynes at a pic of the engine with the head off, the two centre pistons look the same height and the two outer pistons look the same height, coupled with the fact that the two HT leads coming from one coil attach to pistons of the same height would suggest they fire at the same time yet the same manual gives the firing order of 1-2-4-3 ???? how can this be??

Kickstart · « **Reply #12 on:** November 13, 2005, 01:22:29 PM »

Hi

They do fire at the same time, but remember it is a 4 stroke so only every other time the piston reaches the top is it compressing the mixture and needing to ignite it (the other times it is getting rid of the exhaust gases). Most bikes run a wasted spark system, so the 2 cylinders reaching TDC at the same time both receive a spark, but one of them is totally wasted (a lot simpler than using a single coil per cylinder or faffing round with a distributer).

All the best

Keith

duck · « **Reply #13 on:** November 13, 2005, 01:35:41 PM »

so why do you think when i swapped the leads over the other cylinder went dead?? the other day the secondary circuit tested well within limits (32kohms i think) and we're getting a spark on that lead???

i've never seen anything like it

elofdahl · « **Reply #14 on:** November 13, 2005, 02:40:19 PM »

Quote from: "duck"

so why do you think when i swapped the leads over the other cylinder went dead??

The problem may be following a bad spark plug cap (arcing to ground in the head's "tunnel").